Radionuclide imaging, including single photon emission computed tomography (SPECT) and Positron emission tomography (PET), etc., is a quantitative technology for imaging metabolic pathways and dynamic processes in vivo. It may reflect the change of cell metabolism and function at the molecular level. In a clinical environment, radionuclide images may be interpreted visually to assess the physiologic function of tissues, organs, and/or organ systems. Magnetic resonance (MR) imaging may provide versatile soft-tissue contrast, yielding diagnostic accuracy without exposing a patient to ionizing radiation. The combination of PET imaging and MR imaging may provide many advantages such as higher soft-tissue contrast, reduced radiation exposure, and advanced MR imaging techniques such as diffusion imaging, perfusion imaging, and MR spectroscopy. However, the combination is challenging because of low signal intensity of cortical bone in conventional MR imaging. Low signal intensity of cortical bone makes it difficult to differentiate bone tissue from air cavities in MR imaging.
Thus, there exists a need in the field to provide a method and system for the separation of bone and air in MR image.